Touch activated controller and method

ABSTRACT

A touch activated controller generates UP/DOWN control signals in response to movement of a human finger (or other comparable contact) along a control surface thereof. The UP information is derived from movement of the finger in one direction and the DOWN information is derived from movement in a substantially opposite direction. This system generates a sequence of control signals in one or the other of the two directions. In addition, when the finger is removed from the device the output remains in its last previous state or condition existing before removing the finger. Thus, the logic of the system is sensitive substantially to motion and direction of movement so that the logic of the operation of the device closely resembles the motion of a thumbwheel control. Merely placing a finger on the surface of thumbwheel or on the surface of the disclosed device generates no change in the position of the thumbwheel or the output of the device herein. When a finger is moved in one direction while in contact with the control surface of the device or the thumbwheel the output of the device will generate control signals counting up or down depending on the direction of movement of the finger.

This is a division, of application Ser. No. 897,686, filed Apr. 19,1978, now U.S. Pat. No. 4,221,975.

BACKGROUND OF THE INVENTION

This invention pertains to a touch activated controller and method andmore particularly to a touch activated controller and methodparticularly useful to function as an electronic thumbwheel control.

Heretofore circuits operated in response to the touch have been known.Some of these circuits employ means for introducing energy into thesystem in order to effect their purposes as opposed to the presentsystem wherein energy is taken out of the system as described furtherbelow.

SUMMARY OF THE INVENTION AND OBJECTS

In general, a touch activated controller for generating signals adaptedto be coupled to operate apparatus in response thereto comprises a bodyof insulating material and a series of discrete sense lines formingportions of capacitors carried in closely spaced relation by theinsulation material. Each of the sense lines functions as one plate of acapacitor when in the proximate presence of the person's finger or otherbody portion. A series of discrete sensing circuits are respectivelyassociated with related ones of the sense lines. The circuits serve togenerate a first digital output in response to the absence of a bodyportion at a sense line associated therewith and a second digital outputin response to the presence of a body portion thereat so as to sense andindicate the presence of a body portion in proximity to each of thesense lines. Means are coupled to the last named means for generating asequence of control signals representing increasing or decreasinginformation dependent upon movement of the human finger or other bodypart across the sense lines in one or another of two substantiallyopposite directions.

In general it is an object of the present invention to provide animproved controller device and method capable of being operated bymovement of a person's finger or comparable contact across a controlsurface without movement of operative parts, other than the person'sfinger.

It is another object of the present invention to provide such a touchactivated circuit which is significantly more sensitive to the contactof a person's finger so that very small sensor lines can be employed andhence packed very closely together. In this manner greater resolutioncan be obtained.

Another object of the invention is to provide a touch activatedcontroller and method in which the output information generated forcontrolling devices is made to vary at a rate and to a degreecorresponding to that of the movement of a person's finger across thecontrol surface of a touch activated controller.

Yet another object of the invention is to provide a touch activatedcontroller employing a minimum of detector circuits each cooperatingwith a plurality of sense lines or inputs.

Yet an additional object of the invention is to provide a touchactivated controller in which the digital output information is causedto vary in response to the rate and displacement of finger movementalong a series of sensing elements as detected by comparing the resultsof past sensing status with present sensing status so as to createsomething of an electronic "thumbwheel".

Yet a further object of the invention is to provide a touch activatedcircuit in which no direct electrical contact is required to be made bythe operator.

The foregoing and other objects of the invention will become moreclearly evident from the following detailed description of a preferredembodiment when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic perspective view partially broken away of atouch activated controller system according to the invention;

FIG. 2 shows a diagrammatic top plan view partially broken away of atouch activated controller according to the invention;

FIG. 3 shows a side elevation diagrammatic view of FIG. 2 according tothe invention;

FIG. 4 shows a diagrammatic perspective view, as viewed from beneath, ofan intermediate substrate portion of the touch activated controllerdevice as shown in FIGS. 1 through 3;

FIG. 5 shows a diagrammatic side elevation section view of a portion ofthe substrate of FIG. 4 but with the conductive channels of theunderside of the substrate being diagrammatically shown disposed inexploded relation away from the level of the layer of the substrate forillustration and also including a series of circuits disposed in anexploded perspective arrangement for explanation purposes only;

FIGS. 6 and 7 show diagrammatic graphs employed in the explanation ofthe functioning of a circuit of the type shown in FIG. 5;

FIG. 8 shows a diagrammatic block diagram of the overall systemaccording to the invention;

FIG. 9 shows a timing diagram for use in conjunction with the masterclock of FIG. 8; and

FIG. 10 shows a series of charts representative of the signals appearingat various outputs of the two shift registers of the system as well asproviding pulses representative of the exclusive OR function, all asoccurring in the system according to FIG. 8.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

As shown in FIG. 1 a touch activated controller system 10 is shown of atype for generating a sequence of control signals via output leads 11,12 wherein the sequence of control signals represents increasing ordecreasing information depending upon the direction of movement of aperson's finger 13 or other body part across the surface 14 of thecontroller assembly 16. In general, controller assembly 16 includes asupport body 17 which carries a layer 18 of insulating material of atype adapted to receive printed circuit elements and leads on top and onthe bottom.

A series of conductive elements 19 disposed transversely upon theobverse surface of layer 18 using known printed circuit techniques arearranged in uniformly spaced apart relation distributed along the lengthof the top of layer 18. A series of conductors 21 carried on the reverseside of layer 18 extend longitudinally therealong substantially normalto the direction of the conductive elements 19. Conductors 21 are spacedsubstantially uniformly apart laterally across the width of the reverseside of layer 18 so that conventional lead through connections 22 canserve to interconnect successive ones of elements 19 to successive onesof conductors 21.

That portion of layer 18 which carries conductive elements 19 issubdivided into seven groups 72 (FIG. 8) of fifteen elements 19 each.The first element 19 of each group is connected by means of aconventional lead through connection 22 to a common one of the fifteenconductors running longitudinally beneath layer 18. Similarly, thesecond element of each group is connected to a second common one of thefifteen longitudinal conductors, and so on. Accordingly, as thusarranged, the lead through connections 22 provide means interconnectingsuccessive ones of the conductive elements 19 to successive ones of theconductors 21.

A plastic protective layer 23 having a thickness of the order of 0.003of an inch overlays the top surface of layer 18 so as to provide asmooth surface upon which a finger may be placed and also providing aninsulating barrier preventing electrical contact between the finger andthe electrical conductive elements 19.

Controller assembly 16 further includes circuitry 24 as describedfurther below in the form of one or more monolythic integrated circuitchips and other microminiature electronic components. Components 25 asshown only represent these circuit components and do not show the actualplacement of said components within the assembly. Components 25 merelyserve as a representation of components employed in the system as shownin FIG. 8.

The controller unit 16 as thus arranged can be plugged into a systemwherein the pins 26 cooperate with a suitable power supply and twogroups 27, 28 of pins supply a first and second binary coded decimaldigit via leads 29, 31 to form the input to conventional conversionunits 32, 33. Units 32, 33 convert the binary coded decimal input to aseven segment output signal on output lines 11 and 12 for operating theseven segment displays 34, 36 associated respectively with the first andsecond decimal digits. These seven segment displays, as is known, arecapable of clearly displaying the digits from 0 to 9.

As shown in FIG. 4 body 17 has been removed for clarity so that theconnections to circuitry 24 and associated electronic elementsrepresented diagrammatically by elements such as 25 can be more readilyobserved.

As an activator, such as a person's finger, moves along surface 14passive elements 19 provide active inputs to the system. Thus, thefinger serves to complete the formation of a capacitor coupled as aninput to each of a number of sensing circuits 40. Thus a human finger 13activates each input 41-55 since the finger forming a pad with uniformminimum spacing (defined by layer 23) between the surface of the skinover a broad area of conductive elements 19. In this way portions of theskin area can be considered to constitute the equivalent of a plate of acapacitor while the conductive elements 19 serve to form the other plateso that upon disposing the finger in the proximate presence of element19 a capacitor is formed coupled to ground via the body.

While an equivalent form of contact or other activator can be formed tooperate the system herein, the present system will be described withrespect to its operation in response to movements of a finger across thesurface 14 of layer 23 having in mind that other types of activator canalso be used to develop similar inputs.

Inasmuch as elements 19 are used to sense the presence or absence of afinger (or other comparable contact) these elements are referred tohereinafter as sense lines.

A plurality of touch activated circuit means 40 associated with each ofthe plurality of sense lines 19 serve to provide a digital output of "1"or "0" with respect to the status of each sense line associatedtherewith. A digital "1" indicates the proximate presence of a person'sfinger in association with the given sense line, and a "0" the absence.

Each of a plurality of touch activated circuits 40 is associated with aplurality of related sense lines.

As described further below, the output of the system will remainconstant in the event there is no movement, (just as a thumbwheelstanding still). Thus, sufficient spread must exist between the firstand the last sense line 19 in each group so that there is littlelikelihood that the finger will cover all sense lines simultaneously.With all lines 19 covered it is not possible to determine motion of thefinger using the arrangement described further below. Thus, the spreadbetween the first and last sense line within each group thereof isdeemed to be a "maximum fingerprint" 72. Note that all circuits are thesame. However, to assist in explanation their input leads 41-55 areshown. Accordingly, these leads are each coupled to an associatedcircuit 40 to provide an input thereto. Inasmuch as each of the touchactivated circuits 40 associated with input lines 41-55 is the same adescription of a single circuit 40 is believed to be a sufficientdescription of the remaining circuits 40 herein.

Operation of each circuit 40 is dependent upon the fact that thepresence of a person's finger (or other comparable object) in closerelation to any one of the sense lines 19 serves to create something ofa limited capacitance therewith in which the associated sense line 19constitutes one of the two plates of a capacitor while the person'sfinger constitutes the other plate coupled to ground through the fingeras shown in FIG. 5. It is not necessary for the finger to have anyelectrically conductive path connected to ground either directly orthrough the person, since a human will necessarily have a relativelylarge capacity to ground by virtue of the large physical size withrelation to the capacitors found between the finger and the sense lines.This large capacity to ground effectively renders the finger to be atground potential.

Circuits 40 are arranged whereby in the absence of a capacitance locatedon the input leads 41-55 thereof the output lead 57 will provide adigital zero. On the other hand when a person's finger is sufficientlyclose to one of the sense lines 19, i.e. to be in the "proximatepresence" of a sense line 19, so as to cause it to constitute acapacitance on the input line of the circuit, the output on lead 57becomes a digital "1" as now to be described.

With reference to each of the circuits 40 it is evident that a voltagedivider comprised of resistors 58, 59, 61 provides a first voltage levelat point 62 which is higher than the voltage level provided on line 63.A signal of substantially two volts amplitude and substantially 20 khzfrequency is impressed upon the voltage levels at point 62 and line 63by means of an oscillating signal 64a via lead 64 from a master clock91. This signal 64a appears on both lines 62 and 63 equally via the pairof capacitors 66, 67 connected in common to load 64. The only differencebetween the signals on 62 and 63 is that the voltage at 63 is normallyinstantaneously slightly below that of the voltage at 62. Thisrelationship is shown in the graph of FIG. 6 wherein a trace 68 of thevoltage on lead 63 follows trace 68 but represents the voltage at point62 so as to remain slightly below trace 69.

When sense line 19 is not in the proximate presence of a finger theresulting value of capacitance associated with input line 41 (or inputlines 42-55 for the remaining circuits 40) is zero or near zero. Underthese conditions, the voltage at 38 from operational amplifier 37 willbe at or nearly equal to the voltage at 62.

When a sense line 19 associated with input 41 is "touched" the inputcapacitance developed on lead 41 takes a value of the order of 2 pf(pico farad). By supplying a capacitor 70 also of substantially 2 pf,the output of operational amplifier 37 becomes substantially greater.For example, as shown with regard to the graph in FIG. 7 it will benoted that when the amplitude of the output on lead 38 from operationalamplifier 37 is larger (as occurs when the sense lines 19 are active)the voltage of a portion of each cycle (indicated by the time between t₁and t₂ and the time between t₃ and t₄) drops (along trace 69') below thevoltage of trace 68'. During these times comparator 71 indicates thatvoltage on trace 69' is less than the voltage on trace 68'. At thispoint its output on lead 57 changes from a digital "0" to a digital "1".

As shown in FIG. 8 a series of fifteen touch activated input amplifiercircuits 40 (with associated input lines 41 through 55) are each coupledto an associated one of sense lines 19 from each of the plurality ofgroups 72 thereof to cyclically provide digital input data to the systemas a person's finger moves along surface 14 sequentially activatingamplifiers 40 in each group 72 and as finger 13 moves from group togroup.

The system shown in FIG. 8 comprises a first shift register 76 whichconstitutes a so-called "present register", i.e. the data in register 76represents the present position of the finger 13 along surface 14. Shiftregister 76 is parallel loaded with a pattern of binary digitsrepresenting activated and inactivated outputs 57 as above described.The sequence of parallel loading and the like is described furtherbelow. At this point, it is to be noted that the input signal on entrylead 57 is also coupled via line 78 to constitute a corresponding entryat the 16th stage of shift register 76.

In order to load all outputs 57 in parallel into shift register 76,signal 64a from master clock 91 is fed in parallel by lead 64 to each ofcircuits 40. As explained above with respect to FIGS. 5 and 7 a digital"1" will be generated from each circuit 40 whenever the voltage at point62 drops below the voltage on line 63. The parallel loading of register76 is timed under control of a load command pulse 82 from master clock91 delivered to register 76 via lead 83. The load command pulse occurssometimes between t₁ and t₂ (or t₃ and t₄) such that if the sensecircuitry is activated, a digital "1" will be parallel loaded in shiftregister 76, and if the sense circuitry is not activated, a digital "0"will be parallel loaded into shift register 76.

The sixteen stages of register 76 are numbered 1-16 respectively. Datain each stage of register 76 is shifted the length of register 76 inresponse to stepping pulses 79 from clock 91 via lead 81.

A second shift register 84 comprised of fifteen stages constitutes aso-called "delayed register" to be used to store prior data from the"present" shift register 76. Thus, when register 76 is parallel loadedregister 84 will contain the pattern which was previously loaded intoregister 76.

In addition data is shifted through register 84 conjointly with 76 bysupplying the same series of stepping pulses 79 via lead 81 both toshift register 76 and also to shift register 84 via the inter-connection86.

Shift register 76 includes a plurality of output stages for comparingthe data at stages 14, 15 and 16 (represented by leads 87, 88, 89)comparing with that of stage 15 in register 84. Inasmuch as eachparallel loading of register 76 serves to establish an informationpattern in fifteen stages thereof to be compared to the fifteen stagesin register 84, lead 88, connected to the fifteenth stage of register 76joins lead 92 so as to constitute the data input to shift register 84whereby the pattern of binary digits in register 76 can be shifted intoregister 84.

In order to be able to make rapid comparisons of the signals applied tothe various input lines 41-55 as a person's finger moves along surface14 the fifteenth output stage of 84 is connected via lead 93 to supplyone of the inputs to each of three exclusive OR circuits 96, 97, 98. Theforegoing exclusive OR circuits serve to provide an output signal of "1"only if the two inputs to the exclusive OR circuit are different.Accordingly, the two inputs to exclusive OR circuit 96 comprise leads 97and 93. For circuit 97 the two inputs are derived from the fifteenthstage of shift register 76 via leads 88, 92 and the second input issupplied via lead 93 representing the fifteenth stage of shift register84. Finally, the two inputs to circuit 98 are derived via lead 89 fromthe sixteenth stage of shift register 76 via line 89 and from thefifteenth stage of shift register 84 via lead 93.

It should be noted that the outputs from stages 14, 15 and 16 differonly in that the output from stage 14 occurs one clock pulse earlierthan that from stage 15, that is, is left shifted on graph of outputversus time, and the output from stage 16 occurs one clock pulse laterthan that from stage 15, i.e. right shifted on a graph of output vs.time.

Exclusive OR circuit 96 compares the left shifted loaded pattern withthe previous loaded pattern. Exclusive OR circuit 97 serves to comparethe loaded pattern with the previously loaded pattern, while circuit 98compares the right shifted loaded pattern with the previous loadedpattern.

Counters 101, 102, 103 serve to count each time that a difference isnoted by an associated one of the exclusive OR circuits 96-98 for eachof the fifteen register positions being compared. Clock pulses 94supplied to counters 101-103 via lead 95 serve to "enable" counters101-103 to count once for each clock pulse 94 whenever the associatedinput from exclusive OR circuits 96-98 is high. Counters 101-103 do notcount if the input is low.

The output of counters 101-103 is fed directly to an arithmetic unit 99for processing the input data. In addition, clock 91 also serves vialead 104 to provide a reset pulse 106 to counters 101-103 at a propertime.

Just before the comparison, counters 101-103 are reset to zero. Afterthey have received their fifteenth pulse, a command pulse 107 on lead108 (coupled to arithmetic unit 99) causes unit 99 to put out itsrequired UP/DOWN count by operating on the results of the complete cycleof fifteen comparisons. The output from arithmetic unit 99 appears onlines 109, 111 wherein the UP counting information is transmitted vialine 109 and the down counting information is transmitted via line 111to an UP/DOWN counter 112 in the form of a decade counter. The outputfrom counter 112 provides a first binary coded decimal number on thefour leads 29 and a second binary coded decimal number on the four leads31. Leads 29 and 31 are respectively coupled to an associated binarycoded decimal to seven segment coding units 32, 33 so as to provide adecimal output at each of the two seven segment displays 34, 36.

In operation arithmetic unit 99 performs the following logic andprovides outputs on lines 109, 111 just before counters 101-103 arecleared by reset signal 106 on line 104 every time a pattern of digitalinputs is parallel loaded into shift register 76.

For example, if the count in counter 103 (fed by stage 16 throughexclusive OR circuit 98) is greater than the count of counter 101 (fedby stage 14 via exclusive OR circuit 96) and at the same time the countin counter 103 (fed by stage 15 through exclusive OR circuit 97) exceedsthe count in counter 101 (fed by stage 14 through OR circuit 96), thenthe output is two pulses UP on line 109. The foregoing relationship isrepresented as:

    ______________________________________                                        INPUT                 OUTPUT                                                  ______________________________________                                        {16} · {14} > {15} = {14}                                                                  2 Pulses UP                                             ______________________________________                                    

Thus, the representation A>B means A is greater than B, and the mid-lineperiod symbol (·) represents the logical "AND" symbol which means thatexpressions on both sides of (·) are true.

Thus, the above example "states" that if the value of stage 16 isgreater than the value of stage 14, AND if the value of stage 15 isgreater than that of stage 14, then the output is two pulses UP on line109.

In addition the following logic is performed:

    ______________________________________                                        INPUT                OUTPUT                                                   ______________________________________                                        {16} > {15} · {14} = {15}                                                                 1 Pulse UP                                               {14} > {15} · {16} = {15}                                                                 1 Pulse DOWN                                             {14} > {16} · {15} > {16}                                                                 2 Pulses DOWN                                            ______________________________________                                    

For all other results no pulse is developed.

FIG. 10 employs this logic.

As shown in FIG. 9 a timing diagram is provided indicating the sequenceof operations of the system shown in FIG. 8 as explained above.

The function and operation of the system in FIG. 8 can bediagrammatically indicated by the graphical representations shown inFIG. 10 using the above logic.

For example, as shown in the top row of graphs in FIG. 10, theinformation shown generates no pulse. UP or DOWN since no specific logicline corresponds to the conditions stated specifically in the logicabove.

The information represented in the second row corresponds to the secondline of logic to generate 1 pulse UP.

We claim:
 1. In a touch sensitive circuit comprising an input adapted to be coupled to a sense line for supplying a change in capacitance via said input, an operational amplifier coupled to receive said change via said input, capacitance means coupled across said operational amplifier between the input and output thereof, comparator means coupled to said output of said operational amplifier, means for generating first and second signals at varying voltages normally plottable along substantially parallel traces, means for coupling said first and second signals respectively to supply signals to said operational amplifier and said comparator means to vary said output of said operational amplifier to be compared to said second signal to provide periodic cross-over between said first and second signals indicative of the presence of capacitance applied to the first named said input. 